* Vitol chief Ian Taylor said U.S. crude oil output could rise by 500,000-600,000 bpd next year, pressuring light grades such as those produced by Nigeria.

* OPEC’s Secretary General Mohammed Barkindo on Tuesday called on U.S. shale oil producers to help curtail global oil supply, warning extraordinary measures might be needed next year to sustain the rebalanced market in the medium to long term. (Reporting by Libby George; Editing by Susan Fenton)